It depends whether you mean the original definition of a "fan dipole", or themore recent imposter that consists of multiple half wave dipoles on a commonfeedpoint.

There is no problem combining dipoles for any of the pre-WARC bands (160, 80, 40, 20, 15 and 10m) on a common feedline. 30m doesn't seem to be a problem, either. The closer together you bundle the wires, the more they will interact, and it will take a bit more cut and try to get them tuned, but I've carried sucha set of dipoles in my backpack and strung them up in a number of, um, creative installations, and used them without any further tuning orother adjustment (no antenna tuner, either.)

The 20m, 15m, and 10m bands are a half octave apart. (10m is twice thefrequency of 20m, and 15m is about in the middle.) When you start trying tocombine bands that are closer together than that, the unused elements maynot have a high enough impedance on other bands that it can be ignored. So the main issue will be 20 / 17 / 15 / 12 / 10m.

I was able to model multiple dipoles for 20m / 17m / 15m / 10m with reasonableresults, but once I added wires for 12m everything changed. The SWR dips for20m, 15m and 10m are still visible on the plot, though sometimes shifted aroundby up to 1 MHz, but the 17, and 12m resonances are not at all as one mightexpect.

So if there is one band that causes problems it probably is 12m when used alongwith 15m and/or 10m. Putting 17m on with 20m and/or 15m seems to have abetter chance of success, but still some possible quirks.

With a true fan dipole, however the situation is very different: it can coverall bands from 40m through 10m (as well as frequencies between the bands) with an SWR of 3 : 1 or better. Covering 20, 17, 15, 12 and 10m is trivial, and it canbe extended to add 30m and 40m if space is available.

I may seem to be a bit of a stick-in-the-mud about the names, but the originalfan dipole seems to be forgotten, and it really is a useful antenna, as it allowswideband operation with a built-in antenna tuner that matches up to 3 : 1.It can work over a 3 : 1 or 4 : 1 frequency range with no more effort to build than multiple tuned dipoles. The design has been around since the 1930s, and is covered in Kraus' Antennas, Laporte's Radio Antenna Engineeringand Jasik's Antenna Engineering Handbook. Commercial and militaryversions are available: http://ascsignal.com/files/hf/omin_directional/1765-2012.pdf

Here is an example: cut 10 wires each 25' long. Connect 5 of the wires to eachside of a 6 : 1 balun (as are often sold for OCFD antennas). Spread the wires oneach side out into a fan about 20' wide at the furthest corners. Run coax to therig.

And that is all it needs! The SWR should be below 3 : 1 from 10 to 30 MHz, allowinguse with a limited-range autotuner (or the adjustable output stage in a tube rig)across the entire range. The design can be scaled up or down as needed: actually,except for some small blips near 47, 66 and 85 MHz, my model shows low SWR tobeyond 100 MHz, though the patterns get rather quirky. But a 40m through 10mversion should be practical. A huge advantage in many applications is that thereis no adjustment of lengths required because the antenna isn't tuned to a specificfrequency.

If you don't have a 6 : 1 balun you can use a 4 : 1 and the SWR might rise to 4 : 1instead of 3 : 1, but it is still easy to match and coax losses are reasonable. Youcan try using 75 ohm coax in place of 50 ohm in that case if you have some handy.

You can experiment with different numbers of wires or varying the angle betweenthem and see what works best. Installing it as an inverted vee may make a bettermatch with a 4 : 1 balun.

So that's why the answer depends on what version of fan dipole you are building.

Thanks very much. I have (the former) for 30,20,10 as well as a dipole for 80 (which also works on 17) and I will be putting up one for 40 and 12. I just wanted to know if there were issues combining those two specifically.

Thanks again. Your input on this site is always beneficial to me and I always learn something from it.

well sort of I was not sure whether or not the description pertained to the spacing between each or if it pertained to the longest uppermost horizontal dipole to the lowest highest frequency somewhat inverted dipole on the bottom most opposite extreme.or the first space to the next somewhat inverted V of the next band up.

One design in particular brought to mind utilizes a much smaller almost 50% less vertical spacing from the ends of the upper most to the ends of the lower most wire space.Along with element lengths modified to work in conjunction to the other dipoles being commonly driven and kept at that 38" dimension ect.

a 4 band fan dipole and 1:1 current balun fed with a single 50 ohm coaxial cable used to drive all 4 antennas from a common feed point along With a 6" span vertically spread to equate to and 38" space between each end per half is 38"=3ft 2"= 12 feet 8 inches a long way from 20feet.

Strictly speaking within this antenna there really only exists a dipole for the lowest band since only it can be stretched held parallel to the Earth surface and an somewhat inverted V for the remaining three. because they are hung off a halyard system and deliberately spaced resulting in an inverted v shape

With the 4 band version We can roughly eliminate a total of 4ft from the vertical end seporation.

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